Replacing wheels/ t ires
Vehicles with all-wheel drive must always
have tires of the same size. Also avoid tires
with different tread depths. For details see
page ¢
page 284, New tires and replacing
tires and wheels .
.&_ WARNING
Always adjust your driving to road and traf-
fic condit ions . Do not let the extra safety
afforded by all-wheel dr ive tempt you into
tak ing extra risks.
-Although the all-wheel dr ive is very ef-
fective, always remember that braking
capacity is limited by t ire traction . You
sho uld therefore not dr ive at excessive
speeds on icy or slippery road surfaces.
- On wet road su rfaces, be careful not to
dr ive too fast because t he front wheels
cou ld beg in to s lide on top of the wat er
(aquaplaning). If this sho uld occur, you
will have no warning from a sudden in-
crease in engine speed as with a front-
wheel drive vehicle. Always drive at
speeds wh ich are suited to the road con-
ditions - risk of crash.
Energy management
Starting ability is optimized
Energy management controls the distribution
of electrical energy and thus optimizes the
availability of electrical energy for starting
the engine.
If a vehicle wit h a conventional energy system
is not driven for a long pe riod of time, the bat-
tery is disch ar ged by idling current cons umers
(e.g. immobilizer) . In ce rtain circumstances it
can result in there being insufficient energy
ava ilab le to start the engine .
Int ell igen t energy management in your vehi -
cle hand les the d istribution of electrical ener -
gy. Starting abi lity is marked ly imp roved and
the life of the battery is extended.
Int e llig e nt technolog y 229
Basica lly, energy management consis t s of
batte ry diagnosis, idling current manage-
ment
and dynamic energy management.
Battery diagnosis
Battery diagnosis continuously de t ermines
the state of the battery . Sensors determine
batte ry voltage, battery current and battery
temperature . This determines the current
state of charge and the power of the battery.
Idling current management
Id ling cur ren t man agement reduces energy
consumption while the vehi cle is standing.
With the ignition switched off, it controls the
energy supply to the various electrical compo-
nents. Data from battery diagnos is is cons id-
ered.
Depend ing on the battery's state of cha rge,
individual cons umers are gradually turned off
to prevent excessive discharge of the battery
and thus maintain starting capability.
Dynamic energy management
While the vehicle is being driven, dynamic en -
ergy management distrib utes the energy ge n-
erated according to the needs of the individ u-
al components. It regulates consumption, so
that more electrical energy is not being used
than is be ing generated and ensures an opti-
mal state of charge for the battery .
(D Tips
- But even e nergy management cannot
negate the limits of physics. Consider
t hat the powe r and life of a bat t ery are
limited.
- If start ing ability is threatened, you are
informed by a warning ¢
page 230,
Driver notification in the instrument
cluster display.
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